/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.zhaohg.spark.examples.ml;

// $example on$

import org.apache.spark.ml.feature.HashingTF;
import org.apache.spark.ml.feature.IDF;
import org.apache.spark.ml.feature.IDFModel;
import org.apache.spark.ml.feature.Tokenizer;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.RowFactory;
import org.apache.spark.sql.SparkSession;
import org.apache.spark.sql.types.DataTypes;
import org.apache.spark.sql.types.Metadata;
import org.apache.spark.sql.types.StructField;
import org.apache.spark.sql.types.StructType;

import java.util.Arrays;
import java.util.List;
// $example off$

public class JavaTfIdfExample {
    public static void main(String[] args) {
        SparkSession spark = SparkSession
                .builder()
                .appName("JavaTfIdfExample")
                .getOrCreate();

        // $example on$
        List<Row> data = Arrays.asList(
                RowFactory.create(0.0, "Hi I heard about Spark"),
                RowFactory.create(0.0, "I wish Java could use case classes"),
                RowFactory.create(1.0, "Logistic regression models are neat")
        );
        StructType schema = new StructType(new StructField[]{
                new StructField("label", DataTypes.DoubleType, false, Metadata.empty()),
                new StructField("sentence", DataTypes.StringType, false, Metadata.empty())
        });
        Dataset<Row> sentenceData = spark.createDataFrame(data, schema);

        Tokenizer tokenizer = new Tokenizer().setInputCol("sentence").setOutputCol("words");
        Dataset<Row> wordsData = tokenizer.transform(sentenceData);

        int numFeatures = 20;
        HashingTF hashingTF = new HashingTF()
                .setInputCol("words")
                .setOutputCol("rawFeatures")
                .setNumFeatures(numFeatures);

        Dataset<Row> featurizedData = hashingTF.transform(wordsData);
        // alternatively, CountVectorizer can also be used to get term frequency vectors

        IDF idf = new IDF().setInputCol("rawFeatures").setOutputCol("features");
        IDFModel idfModel = idf.fit(featurizedData);

        Dataset<Row> rescaledData = idfModel.transform(featurizedData);
        rescaledData.select("label", "features").show();
        // $example off$

        spark.stop();
    }
}
